Para-aminodiphenylamin sulfonic acid and process of making the same.



To all u'ihom it may 'concem:

UNITED s'rA'rEs PATENT OFFICE;

ERNsr'EnDMANmoF HALLE-ON-THE-SAALE, GERMANY, ASSIGNOR T AGTIEN GESELL- 'sonAF'r FUR ANILIN FABnIKA'rIoN, or HALLE-ON-THE-SAALE, GERMAN-Yf Specification of Letters Patent.

enria-mmom'rimnynmni sULronrc ACID .AnD raoonss 0F Maxine sum.

Patented pct. 22, 1907. 7

Application filed November 19. 1906. Serial lio- 354.1%7- Specimens.)

Be it known that I, Enxsr Elton Alan, of Halle -onthe Saale,,lVIaigarethen street-1, German Empire; have invented new and useful Improvements in New Para Aniinodiphenylaniin Sulionic Acid and Processes of Making Same; and Ildo hereby declare that the following is a full, clear, and exact description thereof, which will enable others skilled in the art to which it apperhim to make and use the same.

Mypresent invention relates to the manufacture of a new-sulfonic acid of para-aminodiphenylaniin it'having been found -that by acting on this amide-compound with mono-hydrate (sulfuric acid containing 100 per cent. H 80 or with a fuming sulfuric acid of suitable concentration, such a new sulfonic acid is obtained. whereas as is well known, by the action of the commercial sulfuric acid of 66 Baurn specific gravity on para-am'inodiphenylamin sulfonation occurs only. to a. very small eXter' t;a11d'w-itl1 the formation of large proportion of by-prodncts. Moreover according to the ",present invention this new sult'onic acid oi para-aminodiphenylamin is obtained with a good yield (7 580% of a theoretical yield and without the occurrence of any considerable,decomposition. The reaction-proceeds according to the following equationz' -sH,'-.c;a,.-mC mma;

i NH .C- H .NH.C H,,.SO H+H,O. to the constitution of the acidit appears to be the parai-aminodiphenylamin-pziraY-sulfonit: acid:

in viewof the fact that, by heating an alkali salt of the I new sulfonic acid with alkalihydroxid and some water a 1 in a closedtube to about 160 C, the product is split up, formingpara-aminophenol at one side and on the other -side sulfanilic acid.

In. carrying out the sulfonation a somewhat higher temperature such as about 100-130 Centigrade must be used. Besides that the temperature as'well'ps'the duration of the reaction depend to some extent upon the strength of the fuming sulfuric acid it such is used. In every case care-must be taken that evolution of sulfur .dioxid occurs only' to a slight extent.-

I introduced thereto while stirring well and care being taken by cooling with cold water that the temperature does" not eiiceed' f centigrade. Now the is times its weight of cold water; the greatest past 'of, the sulf onic acid immediately separates out whereas when the mass .is allowed to stand for sometime a further small part of the acid-precipitates in a' crystalline form. The precipitate is filtered from the solution and washed with cold water; it is preferable to directly purifythe snlforiic acid bydissolvingit in eight times its weight of an aqueous solution of sodium carbonate, containing seven per cent. of the carbonate. From this solution, when necessary after filtration, the pure sulfonic acid is precipitated by the addition ofhydrochloric acid, filtered, washed and dried.

It is convenient to'say that whereas in the-foregoing example the duration of the reaction was at 2-3 hours,

the reaction-may be performed in less time and also the temherature inay be somewhat diminished, if fuming sulfuric acid is used; for instance when using a fumiiig .lieated in an oil-bath F012;? 'centigiade till a sample, of the melt dissolves totally in soda solution. Thisoccurs after 2 to 3 hours, the melt then being poured into four acid of 8 per cent. strength of sulfur trioxid, the reaction is finished in .2- hours at a temperature of 120 centigrade. In the case of. a funding sulim-ic'acid of 15 per, cent. strength of S0 the reaction takes one hour at 110- 120 centigrade.

The new para-aminodiphenylamin sulionic acid obtained as above is characterized by the following physicaland chemical qualities. in hot water and crystallizes froma'hot aqueous solut in fine needles arranging themselves to a concentric bundle. Y The sodium salt'of the new acid is very easily soluble in water, whereas the potassium salt is It is difli'cultly soluble somewhat less soluble and may therefore be easily o'btained in a pure state. This potassium salt when dried in vacuo has the composition C H N sO K as shown by analysis. I

- The proportion of boiling water which is necessary to dissolve para-aminodiphenylamin sulionic acid is most characteristic forthe new acid; it was found that one partpf the acid needs 125,5 parts of boiling water for dissolution. Also the colorations are characteristic which are produced in a dilute aqueous solution of the sulfonic acid by theaction of oxidizing agents; ferric chlorid when added .to such an-aqueoussolution at ordinary temperature causes a red-yellow coloration, the same is the casewith a mixture of potassium bichromate and .acetic acid. Finally by the action of nitrous acid on this aniido-sulfonic acid in the usual manner there 'is obtained a diazo-compound which separates from the aqueous solution as a yellow and crystalline nor tov the details'given therein As alreadystatedthe duration oi the heating and more" especially the tempemturc. at which the reaction is carried out depend to a great deal upon the strength of the sulfuric -acid i. e. the percentage of sulfur trioxid. Generally speaking the use of a stronger fuining'snlfurio acid will allow either to diminish the duration of the heating or to perform the reaction at- :i somewhat lower temperature, but on the other hand the percentage of the fuming acidmay not exceed a certain strength and this limit lies zit-about 20 per cent. of S0 As to the purification of the para ainiinodiphenylamin-siilfonic acid in may of course be performed in any suitable wayotiier than that given in the example.

Having now described my invention and the manner in wh ich the same is to be performed what I chrini is l. The hereinbefoie described process of producing anew f1:321rzraminodiphenylamin sulfonic acid, which is the para aminodiphenylamin para sult'onic acid and which process consists in heating puru-zlminodiphcnylumin with a concentrated sulfuric acid containing between 0 and 20% of free sulfur trioxid to temperatures between 101) and 130 degrees centigrade.

lan

2. As a new composition of nmtter'a pr.rn-nmiuodiphcnylnmin snlfonic acid which is the para-nminodiphcnyhuninpzirzV-sulfonic acid and which n'c'l may he obinincd by the action of monohydrntc sulfuric flL'ifl'Oll :ll';l-:ll1lill0- diphenylamin at 125 'centigrndc for 2 to 7% hours. and

which new sulfonicncid is ditficultly soluble in hot water new puru :ilninodiphenylumin sulfonic acid by the action.

of nitrous acid in the usuz ll'innnncr being convcrlcd into a dime compound possessing a yellow color and being diff cultly soluble in water.

in witness whereof I hnrc hereunto signed iny mime, in the presence of two subscribing wiinossosf i ERNST EIIDUANX. Witness Iii'DHLlii l-nn'zui. Smrirmn l'. \\'.\1:xi:n. 

